Fallen leaves should be removed from a lawn soon after they fall, both for aesthetics and for the health of the lawn. Delaying their removal allows dew and rain on the fallen leaves to hasten their partial decomposition, which exacerbates their removal. Organizing people to periodically rake or blow a lawn can be expensive.
An automated technique for clearing leaves and other debris from lawns has similarities to robotic lawn mowers, such as described in U.S. Patent Application Publication 2004/0133316. There are also analogies to robotic vacuums for cleaning interior floors, exemplified by U.S. Pat. No. 7,024,278 pertaining to the Roomba vacuuming product.
Fallen leaves can be moved mechanically, as with a rake. They can be moved by pneumatic suction, as with a vacuum. They can be moved by pneumatic pressure, as with a blower. Blowers have proven to combine the best time efficiency for clearing leaves with low damage to the lawn and low susceptibility to clogging and fouling. However the technique of blowing is significantly more problematic for an automated technique than vacuuming, for at least three reasons. Blown leaves must generally be directed towards a target deposit area during the entire clearing process, instead of being picked into a hopper and later dumped. The order of what parts of an area should be cleared first matters, since leaves should generally not be blown onto cleared areas. The direction of motion of the blown leaves is generally different than the direction that the blowing apparatus is physically moving.